Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$143.85	11.709%	$160.6934	$160.69	$160.70	$160.70
Purchase #2	$101.74	8.143%	$110.0247	$110.02	$110.00	$110.00
Purchase #3	$175.64	6.335%	$186.7668	$186.77	$186.75	$186.80
Purchase #4	$98.48	11.476%	$109.7816	$109.78	$109.80	$109.80
Purchase #5	$52.29	3.285%	$54.0077	$54.01	$54.00	$54.00
Purchase #6	$6.52	11.790%	$7.2887	$7.29	$7.30	$7.30
Purchase #7	$118.58	4.143%	$123.4928	$123.49	$123.50	$123.50
7 purchase totals =	$697.10		$752.0557	$752.05	$752.05	$752.10